Bucket-wheel cutter for dredges



NOV- 4, 1969 E. J. voN BOLHAR 3,476,498

BUCKET-WHEEL CUTTER FOR DREDGES Filed Deo. 14, 1966 3 Sheets-Sheet lN0V- 4, 1969 E. J. voN BOLHAR BUCKET-WHEEL CUTTER FOR DREDGES 3Sheets-Sheet Filed Dec. 14. 1966 N0V 4, 1969 E. J. VON BOLHARBUCKET-WHEEL CUTTER FOR DREDGES 3 Sheets-Sheet I5 Filed Dec. 14, 19466JN VEA/T01? 5064,? J l/o/u 50044@ United States Patent O 3,476,498BUCKET-WHEEL CUTTER FOR DREDGES Edgar J. von Bolhar, Severna Park, Md.,assignor to Ellicott Machine Corporation, Baltimore, Md., a corporationof Maryland Filed Dec. 14, 1966, Ser. No. 601,694 Int. Cl. E02f 3/24, 3/92, 7/00 ABSTRACT 'oF THE DISCLOSURE with one perforated wallarrangedlrelative to the olw of material through Vthesuction mouth so asto receive and retain the denser objects loosened by the digging wheel.

This invention generally relates to dredges and more particularly tosuction dredges employing a rotary digging wheel to loosen the materialbeing dredged.

The environment of the present invention is in hydraulic dredges of thetype wherein the material being dredged is` loosenedzby a rotary diggingmeans and channeled to the entrance mouth of a suction pipe. From therotary digging means, water and the material being dredged tare drawnthrough the suction pipe by a centrifugal dredge pump and dischargedinto a discharge pipe through which the dredged material is conducted toan appropriate disposal or storage point. 'Ihe dredge of the presentinvention operates in the usual manner lby swinging the dredge throughan arc of approximately 90 to urge the digging means into engagementwith the material being dredged.

It is among the objects of the present invention to provide` an improvedrotary digging wheel for a dredge..

It is an importantobject of this invention to provide a rotary diggingwheel which digs on both the port and starboard swingof Vthe dredge. `l

It is another object of this invention to provide a novel bucketcleaning apparatus which functions as4 the digging wheel rotates. i

It is a further object of the present invention to provide a rotarydigging wheel dredge which is suitable for use in placer miningoperations.

Further objects and advantages of this invention will appear from thefollowing detailed description and th appended drawing wherein: y t Inthe drawing: v

FIGURE 1 illustrates a dredge apparatus embodying in an overallefficiency for the dredge of somewhere bethe present invention; p FIGURE2 is a partial s'ide elevation of the dredge ladder and digging wheelembodied in the present invention; t

FIGURE 3 is a side elevation of the digging wheel illustrated in FIGURE2;

FIGURE 4 is a cross sectional view of the digging wheel taken along line4-4 of FIGURE 3;

FIGURE 5 is a schematic illustration of a digging wheel incorporating amud-scraper for `the buckets; and,

FIGURE 6 is a schematic illustration of the internal portion of thedigging wheel.

Referring to the drawing, FIGURE 1 illustrates a dredge, generallyindicated at 10, including a hull`12, a deckhouse 14 atop which is apilot house or dredge oper- 3,476,498 Patented Nov. 4 1969 ice atorscompartment 15. From the deckhouse 14 two portions 11 and 13 of the hull12 extend forwardly on both sides of the dredge to form a ladder well 17within which is disposed a cable controlled ladder assembly 16. Theladder assembly 16 includes a pair of spaced apart ladder sections19Aand 21 pivoted to the hull 12 adjacent their inner ends about ahorizontal axis 18.

On the outer free end of the ladder assembly 16 is a rotary diggingwheel, indicated generally at 20, about the circumference of which aredisposed a plurality of digging means in the form of buckets or scoops22. The digging wheel 20 is gear driven through a reduction unit 24 by apair' of hydraulic motors 25, preferably of the radial cylinder, lowspeed type. The material being dredged is loosened by the buckets 22 anddrawn through a suction pipe 27 by a centrifugal dredge pump 28 locatedwithin the deckhouse 14 or within a watertight capsule mounted on theladder assembly 16. From the dredge pump, the loosened material isconducted through a discharge pipe 29 to an appropriate disposal orstorage point.

The dredge is operated in the usual manner by swinging the dredge andladder assembly in an arc to urge the digging wheel 20 into the materialto be dredged, with the length of the arc corresponding to the width ofthe cut. The depth of the cut is controlled by either raising orlowering the ladder assembly 16 by a winch (not shown) in the deckhouse14 connected to the outer free end of the ladder assembly 16 through ahoist cable 31 and pulley block arrangement 32 supported from an A-frame 33.

Swinging movement of the dredge 10 and the digging wheel 20 iscontrolled by alternately winding in and paying out port and starboardswing anchor lines 35 and 36, respectively. The swing anchor lines 35and 36 extend from Iwinches (not shown) located within the deckhouse 14along the ladder assembly 16 and around pulleys on the outer end of theladder assembly 16, such as the starboard swing anchor pulley 38, toswing anchors (not shown) in the water olf to the sides and in front ofthe dredge. The dredge 10 alternately pivots about either one or theother of a pair of port and starboard spuds 39 and 40 respectively asthe ladder and front end portion of the dredge swing through an arc. Thedredge is moved forward by 4alternately raising and lowering the portand starboard spuds 39 and 40 upon completion of a cut.

With theusual rotary cutter `means employed on suction dredges adredging cut can be made in only one direction and upon completion ofthe cut the cutter assembly must be swung back to the starting positionto begin the next Cut. While the return swing can be made at a higherspeed than the dredging cut, the return swing is a nonpro-ductive timeconsuming operation which significantly reduces'the `eiliciency of thedredging operation. With a digging wheel constructed in accordance withthe present invention, a dredging cut can be made in both directions.This improvement increases the productivity and results tween 30 to 50percent so-lids.

Referring to FIGURES 3 and 4, the illustrated digging wheel 20, includesa rotating rim section 42 and a stationary hub housing section 44. Therotating rim section 42 comprises a pair of spaced rim or side plates 46and 47 between which the circumferentially spaced buckets or scoops 22are rigidly secured. Rim plate 46 is rigidly secured at 48 to a shaft 49extending transversely of the ladder `sections 19 and 21 and driven bythe hydraulic motors 25 through gears `50 and 51 of 'the gear reductionunit 24. The gear reduction unit 24 is preferably filled with oil andpressurized to a pressure about 5 p.s.i. above that of the surroundingwater at the dredging depth to prevent contamination of the oil by thesurrounding water.

Each of the buckets 22 includes a bowl portion 55 having a curvedblade-like bottom wall 54 anda cutting portion comprising a symmetricalared lip 53 about the inlet opening to the bowl 55 for loosening thematerial being dredged. The symmetrical cutting lip 53 enables thebuckets 22 to make a digging cut when the wheel is moved in eitherlateral direction perpendicular to its plane of rotation. The radialinner portion of the bowl 55 is open allowing the loosened material topass `betweenthe rim plates 46 and 47 into the stationary hub section 44of -the digging wheel. 7

The stationary hub section 44 is shown schematically in FIGURE 6 andincludes a pair of laterally spaced plates 56 and 57 carrying a bearingassembly 61 within which if.

the shaft `49 is rotatably journalled. The plates 56 and 57 togetherwith a pair of laterally extending walls 58 andf59 define a re-entrantsuction mouth or box 60 into which the loosened material passes from thebuckets 22. The suction pipe 27 is connected to the suction mouth 60through a circular to rectangular transition section 65 coming off ofthe plate 57 on the hub section at an angle of approximately-21. A j fThe hub section 44 also includes a mould plate 68 extending partiallyaround the circumference of the hub section adjacent an arc prescribedby the inner ends of the rotating buckets 22 on the rim section 42. Themould plate 68 forms a temporary bottom for the open inner ends of thebuckets 22. An opening 69 through the mould plate 68 allows the loosenedmaterial to be washed from the buckets 22 into the suction mouth 60` bythe surrounding water.

The illustrated digging Wheel operates rnost effectively when used todredge relatively loose material such as sand or gravel, for once thelip 53 loosens the material, the surrounding water washes many times thevolumetric capacity of the bucket 22 through the bucket into the suctionmouth 60 before that bucket rotates clear of the material being dredged.When operating in sand and gravel relatively large objects such as rocksmay be swept through the buckets 22 into the suction mouth 60. To keepout the largest of these rocks a coarse grate formed by one or moregrizzly bars 63 may be provided to narrow the opening `69 as shown inFIG. 6. Those rocks which enter the suction mouth 60 and which are toobig to pass into the suction pipe 27 become wedged in the transitionsection 65 and are removed from the digging wheel by removing a cleanout plate 72 over an opening in the wall of the transition section. Whenthe suction mouth becomes clogged with rocks, the digging wheel isstopped and raised out of the water whereupon a workman opens the cleanout plate 72 and reaches in through the opening to remove the rockswedged in the transition section 65.

When the digging wheel is used for the placer mining of gold bearinggravel deposits, a chamber 74 is provided in the lower portion of thestationary hub section 44 to serve as a nugget collection box. Thechamber 74 is separated from the suction mouth 60` by a perforatedportion 75 in the bottom Wall 59 of the suction mouth. The perl foratedportion 75 comprises a plurality of openings 76 through the wall 59 asshown in the exploded portion of FIGURE 6. The perforated portion 75 isso positioned relative to the flow of material through the suction mouth60 toward the suction pipe entrance 65 that the inertia of the heavierobjects will cause them to strike the perforated portion. If the objectis a relatively small but dense one such as a gold nugget it will passthrough an opening 76 into the nugget collection box 74. Although othersmall particles of the loosened material may also pass through theseopenings the swirling action in the chamber 74 caused by the rush ofWater through the suction mouth 60 will be suflcient to carry them lbackup into the suction mouth where they will be washed out through thesuction pipe 27. However, this swirling action is not strong enough toprevent the denser gold nuggets from settling to the bottom of thecollection box 74 where they will remain until they can be convenientlyremoved by removing a 'side clean out plate 77 on the digging wheel.When dredging sand and gravel deposits lenses or at pockets of clay andmud are often encountered. Sometimes, before the buckets are actuallypacked full of mud, balls of mudform and tumble about in the turbulentwater in the suction mouth, then shoot'up through the suction pipe 27and accumulate at the entrance to the centrifugal dredge pump 28. Thereis 'no diieulty in forcing these mud bfalls throughthe pump 28l and outthroughthe discharge pipe 29 Lwhen'thebucketss 221emain open to admitsufficient water to wash them through. However, when the buckets becomepacked with mud there is anainsuicient., supply of/water to wash the mudthrough the dredge pump and it becomes clogged stopping the dredgingoperation.

FIGURE 5l schematically illustrates an apparatus 80 for scraping the mudfrom the buckets 22. The scraper apparatus includes a retractable blade82 slidably mounted in a pair of tracks 83 on the hub 44 and a springmeans to bias the outer end of the blade 82 into the path of therotating buckets 22. In the projected position its outer end engages thecurved bottom wall 54 of each bucket i' bowl 55 and scrapes the mudtherefrom vas the bucket rotates past. The curved wall 54 also camstheblade 82 radially inwardly. to its' fully retracted position so thatit will spring radially outwardly into the succeeding bucket.

In order to produce the effect of a single long spring in the limitedspace available within the hub portion 44 of the digging wheel 20, thebiasing means for the scraper blade 82 comprises a pair of coil-likesprings 85 and 87 housed in a pair of cylindrical spring capsules 84 and86 connected together by a lever arm 91. The lever arm '91 is centrallypivotedY to the stationary section44 at 92 with its ends beingpivotally. connected to the left ends of the capsules 84and 86 at93 and94 respectively. The Vright end of capsule 86 is pivotally secured tothe stationary section 44 at 90 while the right end of the springcapsule 84 is pivotally connected at 89 to the blade 82. The extent ofthe blades projection beyond the mould plate 68 is limited by a stop 96on the hub 44 which is engaged by the end of the lever arm 91 during theoutward travel of the blade.

In normal dredging operation the scraper blade 82 is maintained in aretracted position in which its forward end is substantially ush with amould plate 68. An

\' actuator 97 is provided to overcome the springs 85 and 87 to hold theblade 82 in such retracted position. Invthe event the buckets 22 becomeclogged the pump vacuum increases and gives the operator an indicationof the clogged condition. The operator then raises the digging wheelclear of the bottom and slows the wheel down so that the scraper canoperate properly. The actuator 97 is then retracted to allow the scraperto operate.

What is claimed is:

1. A dredge cutter comprising a hub housing, a cutter wheel mounted forrotation about said hub housing,

curved blades mounted circumferentially about said cutter wheel, saidhub housing having a suction mouth adapted to be connected to dredgesuction apparatus, said suction mouth terminating at the periphery ofsaid hub housing on an arc described by the inner ends of said curvedblades in their travel about said hub housing, scraper means mounted onsaid hub housing, said scraper means including a retractable scraperblade biased to project radially from said hub housing and into therotary path of said curved blades upon rotation of said cutter wheelabout said hub housing whereby rotational movement of said cutter wheelon said hub housing causes each curved blade to overcome the bias ofsaid scraper blade andl move itfradially inward into the housing and atthe same time scrape material being dug from said curved blade into saidhub housing, said scraper means including scraper blade biasing meansfor said retractable scraper blade comprising a pair of springsinterconnected by a pivoted lever, one end of one of said springs beingxed relative to said hub housing and one end of the other of saidsprings engaging said scraper blade.

2. A dredge cutter according to claim 1 wherein said scraper meansincludes stop means interacting between said hub housing and saidscraper means to limit the outward movement of said retractable blade.

3. A dredge cutter as set forth in claim 2, wherein a portion of saidpivoted lever of said scraper blade biasing means engages said stopmeans to limit the movement of said retractable scraper blade.

4. A dredge cutter as set forth in claim 1, wherein said curved bladeforms a wall of a bucket.

5. A dredge cutter as set forth in claim 1, wherein power operatedretraction means are provided to overcome the bias of said springs andto cause retraction of said scraper blade, said spring means normallybiasing said retractable scraper blade outwardly from said hub housing.

6. A dredge cutter as set forth in claim 1, wherein said suction mouthassembly has a substantially rectangular outer mouth portion at theouter periphery of said hub, said suction mouth having a lower edgeopening at said periphery below the axis rotation of said cutter wheel,said suction mouth having its upper edge opening at said periphery abovethe axis of rotation of said cutter wheel, said upper edge and saidlower edge being circumferentially spaced a distance greater than thecircumferential distance from one of said curved blades to the nextcircumferentially adjacent of said curved blades, said suction mouthbeing adapted to receive a suction pipe at a junction point entirelybelow the axis of rotation of said cutter wheel.

7. A dredge cutter according to claim 6, wherein said suction mouth hasa collecting chamber below the junction with said suction pipe, saidchamber being separated from said suction apparatus by a perforatedportion in the bottom wall of the said suction mouth, said perforatedportion being positioned relative to the fiow of material through saidsuction mouth towards said suction pipe that the relative density ofheavier dredged particles will cause them to strike the perforatedportion, said perforated portion permitting relatively small but denseparticles to pass into said chamber and be collected therein.

8. A dredge comprising a hull including forward por tions along eachside of the hull to provide a well for a dredge ladder, a dredge ladderpivotally mounted on the hull for raising and lowering within the ladderwell, said dredge ladder comprising spaced elongated ladder sections, arotatable shaft extending transversely between said ladder sections atthe outer end thereof, a rotatable bucket wheel secured to said shaftfor rotation therewith, said bucket wheel having spaced side platemembers to form a passage between said side plate members, a series ofdigging buckets xed to said side plate members, one of said platemembers having `a circular opening, said digging buckets having U-shapedlips forming the mouths of said buckets and said lips aring outwardlybeyond said side plates, said digging buckets being open towards thecenter of said bucket wheel, a suction box mounted within said bucketwheel between the planes of said side plates, said suction box beingpart of a non-rotating hub, supported by said shaft, said suction boxopening adjacent to the inside of said bucket wheel so as to receive allof the dredged material coming through the open side of the diggingbuckets and said passage between said side plates, a suction pipe havingone end thereof connected to said suction box, a suction pump mounted onthe dredge and said suction pipe terminating at the inlet of saidsuction pump, hydraulic motor means carried by said dredge ladderadjacent said bucket wheel, and gearing connecting said hydraulic motorto said shaft to rotate the bucket wheel and discharge dredged materialinto said suction box, said non-rotating hub being adapted to permitaxial movement on said shaft through the said circular opening in saidone of said side plates.

9. A dredge cutter comprising ya cutter wheel having a stationary hubsuction and a rotating rim section fixed to a shaft, said rim sectioncarrying curved blades mounted for rotation about said hub section, saidhub section defining a re-entrant suction mouth connected to a dredgepump, said suction mouth terminating at the periphery of said hubsection adjacent an arc prescribed by the inner ends of said curvedblades in their travel about said hub section whereby the material beingscooped up by said curved blades is sucked from said suction mouth intoa suction pipe connected thereto by said dredge pump, said hub sectionhaving therein a chamber below said shaft and said suction pipe andbeing separated from said suction mouth by a perforated plate having aplurality of small apertures said perforated plate being so arranged insaid suction -mouth that relatively small but denser particles beingdredged into :said suction mouth will have a tendency to strike it andpass through the openings therethrough into said chamber and becollected therein and removed from time to time.

References Cited UNITED STATES PATENTS 25,875 10/ 1859 Barcroft.

`216,061 6/ 1879 Shaw 37-58 388,252 8/1888 Bowers 37-66 813,252 2/ 1906-Strom 37-66 2,616,560 11/1952' Vogelpoel 209-17 2,722,759 11/ 1955Cosenza 37--66 2,731,741 1/ 1956 Kaufmann 37--54 2,732,641 1/1956Jespersen 37-189 2,826,839 3/ 1958 Kolbe 37-190 FOREIGN PATENTS 57,0813/1946 Netherlands.

ROBERT E. PULFREY, Primary Examiner C. D. CROWDER, Assistant ExaminerU.S. Cl. X.R.

